Activity of Energy Metabolic Enzymes in Different Coral Species and Populations Provides Evidence for Local Adaptation
Anthropogenic alterations to the Earth system threaten the persistence of coral reef ecosystems, yet pervasive knowledge gaps in basic coral biology prevent accurate measures of coral health prior to mortality. The goal of this thesis is to characterize the metabolic signatures of spatially distinct coral populations adapted to the light regimes of their microenvironments using pathway-specific enzymatic assays. Shallow (3 meters) and deep (5-8 meters) Acropora cervicornis and Porites astreoides populations were sampled at two distinct reef sites: Punta Caracol—a turbid lagoon habitat with large influxes of terrestrial sediments—and Eric Reef—a comparatively pristine open-ocean habitat characterized by greater water column clarity. Coral tissues collected from Bocas del Toro, Panama were homogenized and prepared for analysis at Scripps Institution of Oceanography (San Diego). Malate dehydrogenase (MDH), lactate dehydrogenase (LDH), strombine dehydrogenase (SDH), alanopine dehydrogenase (ADH), and citrate synthase (CS) enzymatic assays were employed to represent maximum fermentative and aerobic metabolic capacities by measuring changes in peak absorbance readings via spectrophotometry. Maximum changes in absorbance were standardized against actual protein concentrations in a novel methodology developed for this thesis. Calculated maximum enzymatic activities indicate that the energy metabolic pathways of A. cervicornis and P. astreoides are tuned to local environmental conditions that, generally, favor fermentation in Punta Caracol as suggested by the higher activities of the various opine dehydrogenases.